Pioneer Post-Mortem

The moon-probe Pioneer, which burned out over the South Pacific after staying in space for 43 hours, rose 79,000 miles--or only one-third of the distance to the moon. But it made a much nearer miss than the figures seem to show. The earth's gravitational field drops off with the square of the distance. With only 2% more thrust or only about 580 more m.p.h. peak velocity. Pioneer could have passed the moon* and escaped from the earth forever.

The reason that Pioneer lacked those few more miles of speed is still being debated by the rocket experts. The official explanation, that its first stage climbed too steeply and so did not benefit fully from the speed of the earth's rotation, is not accepted by all. Another possibility is that some of the liquid fuel in the second-stage tanks failed to burn. A third theory is that the solid fuel in the third-stage rocket became chilled before firing and therefore did not give the expected amount of energy.

As Pioneer faltered and began to fall back, scientists at tracking stations tried to fire the Stage Four rocket in the hope it would send the probe into an orbit around the earth. The rocket did not fire. The official theory is that the interior temperature of the Pioneer fell so low (35DEGF.) that its battery lost power and could not work the firing system. Some experts have suggested a simpler cause: a broken electrical connection.

Full explanation of the Pioneer's two-day venture into space must await careful analysis of the data on its flight. Overeager public-relations officers pushed into print a statement that Pioneer had shown that the radiation belt around the earth falls off sharply from 4 roentgens per hour at 5,000 miles to 2 roentgens per hour at 17,000 miles, and that this meant that future space wayfarers should not have much to fear from radiation. But the project's scientists promptly warned that such apparent discoveries may prove to be the result of instrument failure or a drop in the power supply of the recording apparatus. The definitive report on Pioneer's findings may not be released for weeks or months.

One accomplishment of the Pioneer could be told at once. While it was high in space, the operators on its tracking stations gaily used it as a radio relay, e.g., England talked to Hawaii on the other side of the earth, the waves climbing up to the Pioneer and down again. This dramatized the often discussed possibility of using satellites as relay points for the earth's communications.

* Pioneer's failure to circumnavigate the moon reminded at least one British columnist of a quatrain that Poet Edmund Gosse (1849-1928) claimed was written by his housemaid ad found under her mattress: O moon, when I look on thy beautiful face Careering along through the boundries of space The thought has quite frequently come in my mind. If I'll ever gaze on thy glorious behind.

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